Objective: The energy density (kilocalories per gram) of foods influences short-term energy intake. This 1-year clinical trial tested the effect on weight loss of a diet incorporating one or two servings per day of foods equal in energy but differing in energy density.
Research methods and procedures: Dietitians instructed 200 overweight and obese women and men to follow an exchange-based energy-restricted diet. Additionally, subjects were randomized to consume daily either one or two servings of low energy-dense soup, two servings of high energy-dense snack foods, or no special food (comparison group).
Results: All four groups showed significant weight loss at 6 months that was well maintained at 12 months. The magnitude of weight loss, however, differed by group (p=0.006). At 1 year, weight loss in the comparison (8.1+/-1.1 kg) and two-soup (7.2+/-0.9 kg) groups was significantly greater than that in the two-snack group (4.8+/-0.7 kg); weight loss in the one-soup group (6.1+/-1.1 kg) did not differ significantly from other groups. Weight loss was significantly correlated with the decrease in dietary energy density from baseline at 1 and 2 months (p=0.0001) but not at 6 and 12 months.
Discussion: On an energy-restricted diet, consuming two servings of low energy-dense soup daily led to 50% greater weight loss than consuming the same amount of energy as high energy-dense snack food. Regularly consuming foods that are low in energy density can be an effective strategy for weight management.